1. Field of the Invention
The present invention relates to an auxiliary power unit and image forming apparatus.
2. Description of the Related Art
Image forming apparatuses are provided with an image forming unit for forming a toner image on a record medium and a fuser unit or the like for fixing the toner image by pressing and heating the record medium on which the toner image is formed. The fuser unit includes fusing rollers for heating the record medium, and these fusing rollers are heated to a predetermined temperature by a heater. In so doing, the heater consumes a significant amount of power.
In image forming apparatuses, especially in high-speed image forming apparatuses, the electric power may sometimes be set to 200 V in order to obtain a high power. A commercial power typically used in offices in Japan is 100 V (15 A). In order to set the power of an image forming apparatus to 200 V, thus, a special electric work needs to be performed with respect to the power supply facility at the place where the image forming apparatus is installed. This is not convenient, and is not an effective way to cope with the situation.
Some image forming apparatuses thus use a 100-V power, and drop the speed of image formation or temporarily suspend the operation of image formation when the temperature of the fusing rollers drops to such temperature as to cause a failure of fusing due to the lack of electric power supply. This however reduces productivity. It should be noted that the time required for the fusing rollers to reach a predetermined temperature after the power-on is dependent on the capacity of the power supply. Because of this, the operation of image formation cannot be performed for a longer period of time until the fusing rollers reach a predetermined temperature than when a 200-V power is used. This is another factor to reduce the productivity.
[Patent Document 1]Japanese Patent Application Publication No. 58-54367
[Patent Document 2]Japanese Patent Application Publication No. 63-150967
[Patent Document 3]Japanese Patent Application Publication No. 2001-66926
In order to overcome the problem of the lowering of productivity, the technologies disclosed in Patent Document 1, Patent Document 2, and Patent Document 3 may be used.
Patent Document 1 discloses a technology in which a battery is provided as a built-in component in an image forming apparatus, and supplies power to the fuser unit when the temperature of the fusing rollers drops below a predetermined temperature at the time of consecutive copying, thereby eliminating a down time of the image forming apparatus.
Patent Document 2 discloses a technology in which a first heater driven by an alternating current power supply and a second heater driven by a battery charged by a charger are provided, thereby reducing a startup time of the fuser unit.
Patent document 3 discloses a technology in which an auxiliary power is provided detachably for the image forming apparatus, thereby preventing the leakage of the electrolytic solution of the secondary battery from damaging surrounding components.
More often than not, a commercial power supply is not only used for an image forming apparatus but also used for other office equipment attached thereto. In such cases, a large electric current may flow into the breaker at the time of power-on of the image forming apparatus or return from the power consumption mode, resulting in the severing of the breaker. In order to avoid such a problem, typically, the maximum power consumption of the image forming apparatus is specified in the operation manual, catalog, or the like.
Some users (clients) of image forming apparatuses may not feel inconvenience even if the speed of image formation drops at the time of consecutive image formation, or even if there is a break time in the image forming operation. Further, there may be users who do not mind even if the startup time is lengthy. Also, the problem of breaker severing may differ depending on the usage of power supply at user offices. Moreover, if an auxiliary power supply and associated control circuit are provided in an image forming apparatus as in a conventional configuration, an expensive price of the image forming apparatus becomes an issue.
Accordingly, in order to achieve price reduction with respect to image forming apparatuses, it is preferable to add an auxiliary power supply and control circuit or the like in such a manner as to conform to the user usage of the apparatus, user usage of the power supply, user needs, etc.
In this manner, it is desirable to select a balance between higher performance and lower price according to user needs, by providing a unitized structure of an auxiliary power supply and control circuit or the like such that the unit is detachable from the image forming apparatus.
In the case of a unitized structure of an auxiliary power supply and control circuit or the like, the power required by the image forming apparatus is large, so that safety in particular is of prime importance. A conventional unit detachable from an image forming apparatus poses danger if the terminals for electrical connection with the image forming apparatus are touched by a finger or the like after the unit is detached from the image forming apparatus.
Accordingly, there is a need for an auxiliary power supply unit that is safe, and also a need for an image forming apparatus configured such that the auxiliary power supply unit is detachable therefrom.